Skirt type plunger



g- 1954 E. E. STEVENSON SKIRT TYPE PLUNGER Filed Oct. 31, 1951 IN V EN TOR.

\ EDWARD E. STEVENSON ATTORNEY Patented Aug. 3., 1954 sKm'r TYPE PLUNGER Edward E. Stevenson, Whittier, Calif" assignor to United States Steel Corporation, a corporation of New Jersey Application October 31, 1951, Serial No. 254,003

Claims.: (Cl. 103-225) This invention relates to improvements in plungers for subsurface oil well pumps.

Commonly such plungers include a steel tube, aball valve at either or both ends of said tube, and an outer facing of wear resistant material, such as the boron-containing cast iron sold under the trade marks Di-Hard or "I-R Metal." The upper end of the tube is attached to a sucker rod string, which reciprocates the plunger within a pump barrel, and the wear resistant outer facing rides against the interior surface of this barrel.

An object of the present invention is.to provide an improved plunger in which the wear resistant facing is formed on a skirt attached at only its upper end, thus allowing clearance between the plunger tube and the skirt through the remainder of the length of the latter.

A further object is to provide an improved plunger in which torque and tensional stresses are eliminated from the facing of wear resistant material.

A more specific object is to provide an improved mounting for the facing of wear resistant material, which mounting includes a reversible metal sleeve adapted to be threadedly attached at its upper end only and having the wear resistant material bonded or fused to its outer face, there being clearance between the remainder of the sleeve and the plunger tube.

In accomplishing these and other objects of the invention, I have provided improved details of structure, a preferred form of which is shown in the acompanying drawing, in which:

The single figure is a vertical sectional view of a plunger which embodies features of the present invention.

The drawing shows a pump plunger which includes a tube It, a coupling I2 threadedly engaged with the upper end of said tube and a valve cage l3 threadedly engaged with the lower end. The coupling l2 can be attached to a sucker rod string of any standard or desired construction not shown. The plunger reciprocates within a barrel, also of any standard or desired construction but not shown.

In accordance with the present invention the plunger carries an outer skirt which is formed of a metal sleeve l4 and an outer facing l5 of wear resistant material. The sleeve l4 and facing l5 are fused or otherwise permanently bonded together, and the facing preferably has lugs I6 which project into openings in the sleeve to furnish a secure bond. The skirt is reversible end for end, and its sleeve carries internal screw threads I! at opposite ends. The threads at the 2 upper end are engaged with corresponding external threads on the coupling I2. The threads at the lower end are engaged with external threads on a collar it. There is a clearance space l9 between the lower end of the collar I8 and the upper end of the valve cage l3 and a clearance space 20 between the inside of both the collar l8 and the sleeve l4 and the outside of the plunger tube l0.

It is seen that the clearances allow fluid to flow freely into and out of the space between the plunger barrel and skirt. Consequently there is no possibility of a pressure differential building up between the outside and the inside of the skirt. The tension on the plunger during its upstroke is confined to the plunger tube. Likewise there is no torque applied to the skirt, since its lower end is free. The reversibility of the skirt is advantageous in compensating for any unevenness in wear.

While I have shown and described only a single embodiment of the invention, it is apparent that modifications may arise. Therefore, I do not wish to be limited to the disclosure set forth but only by the scope of the appended claims.

I claim:

1. A pump plunger comprising a tube, a' coupling connected to the upper end of said tube, a valve cage carried by said tube, and a reversible skirt formedof a metal sleeve and an outer facing of wear resistant material permanently bonded together surrounding said tube and attached solely by threaded engagement of the upper end of its sleeve with said coupling, there being a clearance space between the inside of said sleeve and the outside of said tube.

2. A pump plunger comprising a tube, a coupling connected to the upper end of said tube, a valve cage carried by the lower end of said tube, a reversible skirt formed of a metal sleeve and an outer facing of wear resistant material permanently bonded together surrounding said tube and attached solely by threaded engagement of the upper end of its sleeve with said coupling, and a collar threadedly attached to the lower end of said sleeve, there being clearance spaces between the lower end of said collar and the upper end of said valve cage and between the inside of said collar and sleeve and the outside of said tube.

3. A skirt for pump plungers comprising a metal sleeve and an outer facing of wear resistant material permanently bonded thereto, said sleeve having internal screw threads at each end for reversibly attaching it to a pump plunger.

4. A skirt for pump plungers comprising a metal sleeve having openings through its wall and an outer facing of wear resistant material having lugs which project into said openings and being permanently bonded to said sleeve, said sleeve having internal screw threads at each end for reversibly attaching it to a pump plunger.

5. A pump plunger comprising a tube, a coupling connected to the upper end of said tube, a valve cage carried by said tube, and a skirt formed of a metal sleeve and an outer facing on said sleeve of material more resistant to wear than the metal of the sleeve and adapted to engage the inside surface of a pump cylinder, said skirt surrounding said tube and being attached solely by threaded engagement of the upper end of its sleeve with said coupling, there being a clearance space between the inside of said sleeve and the outside of said tube, the outside diameter of said skirt at its facing being the maximum outside diameter of the plunger and approaching the inside diameter of the pump cylinder.

References Cited in the file of this patent UNITED STATES PATENTS Number Name' Date 32,831 Greenleaf July 16, 1861 348,881 Bean Sept. 7, 1886 

